1. Field of the Invention
The present invention relates to providing an acoustic diffuser. In particular, the present invention relates to systems and methods for providing an asymmetric cellular acoustic diffuser adapted to diffuse sound waves that encounter a surface. Further, the present invention relates to providing a system of asymmetric cellular acoustic diffusers adapted to diffuse sound waves that encounter one or more surfaces in an acoustic environment.
2. Background and Related Art
Generally, acoustical diffusion is the efficacy by which sound energy propagates in a given acoustic environment, including relatively small spaces, such as a bedroom or a hallway, as well as much larger spaces, such as a concert hall or a sports stadium. A perfectly diffusive acoustic environment is one in which various acoustic properties, such as reverberation time, scattering and absorption, are the same everywhere in the acoustic environment. A non-diffuse acoustic environment, on the other hand, is characterized by considerable disparity in acoustic properties at virtually every discrete location within the acoustic environment. For example, as a listener walks around a non-diffuse acoustic environment while sound waves are being transmitted therein, the listener would detect considerable variations in reverberation time and so forth.
Many acoustic environments, such as a bedroom, are naturally non-diffuse or are not perfectly diffuse. Small acoustic environments, in particular, generally have very poor diffusion characteristics. Poor diffusion characteristics in a given acoustic environment can have significant adverse affects on sound waves transmitted therein leading to various sound aberrations, such as echoes. For example, in a relatively small room, such as a personal home theater, poor diffusion characteristics can degrade the quality and clarity of sound associated with a movie or television show broadcast therein, including degrading the dialogue and musical elements. As a second example, in another relatively small space, such as a small recording studio, poor diffusion characteristics can degrade the quality and clarity of sounds sought to be recorded in such a studio, including the recording of musical instruments as well as singing or spoken words.
Attempts have been made to treat traditionally non-diffuse acoustic environments to thereby improve the diffusion characteristics of such environments. For example, since approximately the 1970's various types of acoustic diffusers have been used in such spaces according to a sequence defined by Manfred R. Schroeder. Generally, an acoustic diffuser will cause sound energy to be reflected in several directions, as opposed to a single direction corresponding roughly to the angle of incidence, thereby leading to a more diffusive acoustic space. However, the performance of current devices, such as quadratic residue diffusers or primitive-root diffusers (also known as phase-grating diffusers) is limited. For example, such devices have equal length cavities across their proximal surface which results in a sympathetic absorptive plane caused by the coupling of the equal cavity lengths. The sympathetic absorptive plane results in increased absorption due to the presence of the equal cavity lengths that affects both the quality and quantity of diffusion or scattering and diminishes the effectiveness of such diffusers by reducing the smoothness of the response and the energy reflected by such devices.
Thus, while techniques currently exist that are used to enhance acoustic diffusion, challenges still exist, including improving scattering and diffusion and reducing or eliminating absorption within the operating range of the diffuser. Accordingly, it would be an improvement in the art to augment or even replace current techniques with other techniques.